Fearful that the elections will be seen as undemocratic, or that turn-out might fall below 50 per cent if the result is considered a foregone conclusion, the Kremlin has persuaded a leading liberal and a host of unknowns to join the race to try to spice it up.

Electoral authorities announced last week that 10 candidates, including Mr Putin, would now run. But analysts say that almost all registered on the instructions of the Kremlin.

One candidate, Sergei Mironov, the Federation Council speaker, inadvertently encapsulated the bizarre nature of this year's presidential election by admitting that he supported Mr Putin.

Explaining his decision to run against Mr Putin, he said: "When a leader who is trusted goes into battle, he must not be left alone. One must stand beside him."

Among the other candidates are a former boxer, a magnate apparently trying to escape prosecution, and an unknown reported to be a stooge for the exiled tycoon Boris Berezovsky.

The only even semi-serious alternative to Mr Putin is Irina Khakamada, a liberal of mixed Russian and Japanese descent. But she failed to be elected to the Duma last time round and lacks even the backing of her own tiny party.

Since he was elected four years ago, Mr Putin has tightened the noose on Russia's free media and sought to crush opposition parties.

But the hard-line tactics have worked almost too well. In parliamentary elections in December pro-Kremlin candidates won more than two-thirds of the seats in the new State Duma.

The results damaged Russia's image abroad where commentators mourned the end of a decade of vibrant, if flawed, post-Soviet democracy. Now the Kremlin is apparently trying to make the presidential election less one-sided.

But all the big-hitters have opted to stay out of the race.

Gennady Zyuganov, the veteran Communist leader who almost ousted Boris Yeltsin in the 1990s, complained the contest was unfair.

Vladimir Zhirinovsky, the ultra-nationalist whose party scored highly in December elections and who almost always supports Mr Putin, appointed his bodyguard, a former boxer, to stand instead of him.

Grigory Yavlinsky, Russia's most prominent liberal and the head of the Yabloko party, refused to appoint a candidate at all, saying the elections are a sham. He lamented Russia's return to what he called Soviet-style one-party rule and likened democracy in Mr Putin's Russia to a Potemkin village.

He added: "I can hardly imagine that Mr Putin is going to have a debate with Mr Zhirinovsky's bodyguard."